Epoxy compounds each having two alicyclic skeletons per  molecule are currently available as a variety of commercial products. Typically, 3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexanecarboxylate is available from Daicel Chemical Industries, Ltd. under the trade name of “CEL-2021P”), 1,2,8,9-diepoxylimonene is available from Daicel Chemical Industries, Ltd. under trade name of “CEL-3000”, and a compound corresponding to a ε-caprolactone oligomer, except with 3,4-epoxycyclohexylmethanol and 3,4-epoxycyclohexanecarboxylic acid bonded to both terminals respectively through ester bonding, is available from Daicel Chemical Industries, Ltd. under the trade name of “CEL-2081”. These epoxy compounds give cured articles through reactions in the presence of various curing agents or curing catalysts. The resulting epoxy resin cured articles have properties originated from resins using compounds having alicyclic skeletons, i.e., thermal stability, transparency, and satisfactory dielectric properties. Accordingly, the epoxy resin cured articles are useful typically as components of coatings, adhesives, inks, and sealants or as intermediates for the production of other compounds that are useful for end uses including pharmaceutical preparations and articles for medical use.
However, 1,2,8,9-diepoxylimonene has methyl groups on carbon atoms constituting the epoxy groups respectively and  thereby has low reactivity due to steric hindrance of the methyl groups. 3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexanecarboxylate and the compound corresponding to a ε-caprolactone oligomer, except with 3,4-epoxycyclohexylmethanol and 3,4-epoxycyclohexanecarboxylic acid bonded to both terminals respectively through ester bonding, are hydrolyzable due to their ester groups in the molecules; and cured articles obtained from these compounds may thereby suffer from deterioration in properties when used typically in hot and humid surroundings or under such conditions as to give a strong acid. Accordingly, demands are made to provide epoxy compounds containing no ester group per molecule but having alicyclic skeletons.
Such alicyclic epoxy compounds having two alicyclic skeletons per molecule but containing no ester group per molecule are disclosed typically in the following documents. For example, Japanese Unexamined Patent Application Publication (JP-A) No. 2004-99467 discloses a process for preparing a 3,4,3′,4′-diepoxybicyclohexyl compound via epoxidation of a bicyclohexyl-3,3′-diene compound with an organic peroxycarboxylic acid. A Russian document (Neftekhimiya, 1972, 12, 353) discloses a process for the preparation of a 3,4,3′,4′-diepoxybicyclohexyl compound via epoxidation of a bicyclohexyl-3,3′-diene compound with t-butyl  hydroperoxide and a catalytic amount of molybdenum(V) chloride. JP-A No. 2004-204228 discloses a curable epoxy resin composition containing a 3,4,3′,4′-diepoxybicyclohexyl compound prepared by the above preparation process, and a cured article from the epoxy resin composition. However, the epoxy resin composition containing the 3,4,3′,4′-diepoxybicyclohexyl compound prepared by the preparation process shows insufficient reactivity upon curing, and the cured article therefrom has not always sufficiently satisfactory properties typically in thermal stability.
Patent Document 1: JP-A No. 2004-99467
Patent Document 2: JP-A No. 2004-204228
Non-patent Document 1: Neftekhimiya, 1972, 12, 353